Trying to force SST to use existing bootstrap stack with custom name

When I try to set the configuration to use existing stack and followed the following docs:

* **`bootstrap`**
  * **`stackName`** The name to use for the SST bootstrap stack
  * **`useCdkBucket`** Use the S3 bucket created by the CDK bootstrap process instead of creating a new one

export default {
  config(_input) {
    return {
      name: "myapp",
      region: "ap-southeast-2",
      bootstrap: {
        stackName: "xxx-xxx-cdk-bootstrap-stack",
         useCdkBucket: true,
       }
    };
  },
  stacks(app) {
    app.stack(API);
  },
} satisfies SSTConfig;

However it forces the stack creation again:

sst deploy --verbose
2023-10-08T23:56:20.191Z   +100ms [debug] Config loaded {"version":"2.26.11","cdkVersion":"2.95.1","constructsVersion":"10.2.69","config":{"name":"myapp","region":"ap-southeast-2","bootstrap":{"stackName":"xxx-xxx-cdk-bootstrap-stack","useCdkBucket":true},"stage":"prakxx5","ssmPrefix":"/sst/myapp/prakxx5/"},"metafile":{"inputs":{"sst.config.ts":{"bytes":314,"imports":[{"path":"sst","kind":"import-statement","external":true},{"path":"./stacks/MyStack","kind":"import-statement","external":true}],"format":"esm"}},"outputs":{".sst.config.1696809380098.mjs":{"imports":[],"exports":["default"],"entryPoint":"sst.config.ts","inputs":{"sst.config.ts":{"bytesInOutput":230}},"bytes":412}}},"paths":{"config":"/Users/prakxx5/genai/sst.config.ts","root":"/Users/prakxx5/genai","out":"/Users/prakxx5/genai/.sst","artifacts":"/Users/prakxx5/genai/.sst/artifacts"}}
2023-10-08T23:56:20.787Z   +596ms [debug] Using AWS profile undefined
2023-10-08T23:56:20.807Z    +20ms [debug] Created AWS client STSClient
2023-10-08T23:56:20.808Z     +1ms [debug] Fetching app metadata
2023-10-08T23:56:20.808Z     +0ms [debug] Initializing bootstrap context
2023-10-08T23:56:20.808Z     +0ms [debug] Created AWS client CloudFormationClient
2023-10-08T23:56:20.920Z   +112ms [debug] Using identity Account: 123121284423 User: AROAWEDGI3FD363WS52YI:AWSCLI-Session
2023-10-08T23:56:20.956Z    +36ms [debug] Loaded bootstrap status
⠇ Deploying bootstrap stack, this only needs to happen once2023-10-08T23:56:21.626Z   +670ms [debug]  ⏳  Bootstrapping environment aws://123121284423/ap-southeast-2...

Please help